Method for producing polycarbonate copolymer

ABSTRACT

A method for producing a polycarbonate copolymer having structural repeating units represented by formulas (I) and (II): 
                         
wherein each of R 1  and R 2 , X, R 3 , R 4 , Y, a to d and n are defined in the application by reacting (A) a dihydric phenol, (B) a phenol-modified diol and (C) a carbonate precursor, wherein the phenol-modified diol is contains 500 ppm by mass or less of a hydroxybenzoic acid.

TECHNICAL FIELD

The present invention relates to a method for producing a polycarbonatecopolymer from a diester diol through interfacial polymerization, tothereby produce a polycarbonate copolymer having a specific structure athigh productivity.

The present invention also relates to a comonomer for producingpolycarbonate resin, the comonomer comprising a high-purity diesterdiol, and to a method for producing the comonomer.

BACKGROUND ART

Polycarbonate (hereinafter may be abbreviated as PC) resins which areformed of an aromatic polycarbonate unit and an aliphatic polyether unitare known to have high toughness. There has been disclosed an exemplarymethod for producing such a polycarbonate, the method includingcopolymerizing a phenol-modified diol (diester diol) which has beenderived from p-hydroxybenzoic acid, an alkyl ester thereof, or an acidchloride thereof, and a diol (see, for example, Patent Document 1).Specifically, PC copolymers produced through copolymerization oftetramethylene glycol (molecular weight: 2,000)-bis(4-hydroxybenzoate)or polyethylene glycol (molecular weight: 8,000)-bis(4-hydroxybenzoate)have been proposed. These PC copolymers formed from a diester diol canbe produced through a conventional interfacial polymerization method.However, during a step of washing polymerization liquid, the methylenechloride phase containing a PC copolymer and the aqueous phasecontaining impurities are difficult to separate from each other. Thus,high-purity PC copolymers fail to be obtained, or high-purity PCcopolymers are produced merely at considerably low productivity, whichis problematic.

Although PC resin is widely employed as a transparent resin having highimpact strength, there is continuous demand for improvement in otherproperties of PC resin. One known approach for improvement iscopolymerization of a compound having a structure other than bisphenol A(e.g., introduction of aliphatic chain), whereby flowability of theresin is enhanced.

In the production method disclosed in Patent Document 1, poly(alkyleneether glycol)-bis(hydroxybenzoate ester) is employed as aphenol-modified diol. Before use, the poly(alkylene etherglycol)-bis(hydroxybenzoate ester) is not subjected to purification.

In addition to production of PC resin, use of poly(alkylene etherglycol)-bis(hydroxybenzoate ester) has been proposed for producingpolyurethane and epoxy resin, and a synthesis method thereof isdisclosed (see, for example, Patent Document 2 or 3). However, thePatent Documents do not disclose purification of the phenol-modifieddiol.

PC resin can be produced through a method such as interfacialpolymerization or melt polymerization. In the case where PC copolymer isproduced through interfacial polymerization of poly(alkylene etherglycol)-bis(hydroxybenzoate ester) serving as a starting material,separation of the aqueous phase from the organic phase performed in thewashing step takes a long time or becomes difficult, which isproblematic.

[Patent Document 1]

-   Japanese Patent Application Laid-Open (kokai) No. 62-79222    [Patent Document 2]-   Japanese Patent Application Laid-Open (kokai) No. 60-79072    [Patent Document 3]-   Japanese Patent Application Laid-Open (kokai) No. 2002-173465

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention has been conceived under such circumstances, andan object of the invention is to provide a method for producing a PCcopolymer having a specific structure from a diester diol serving as astarting material, which method attains enhanced productivity.

Another object of the invention is to provide a comonomer for producinga PC resin, the comonomer comprising a high-purity diester diol, whichfacilitates separation of the aqueous phase and the organic phase duringproduction of a PC copolymer from a diester diol. Still another objectis to provide a method for producing the comonomer.

Means for Solving the Problems

The present inventors have conducted extensive studies in order to solvethe aforementioned problems, and have found that use of a startingmaterial yielded through removal of a specific impurity from aconventionally produced diester diol can remarkably facilitateseparation of the methylene chloride phase containing a PC resin fromthe aqueous phase containing impurities during a step of washingpolymerization liquid.

The present inventors have also found that the aforementioned objectscan be attained by controlling the amount of impurity which originatesfrom synthesis starting material and which is contained in poly(alkyleneether glycol)-bis(hydroxybenzoate ester) represented by formula (IIa)shown hereinbelow. The present invention has been accomplished on thebasis of these findings.

Accordingly, the present invention provides a method for producing apolycarbonate copolymer, a comonomer for producing a polycarbonateresin, and a method for producing the comonomer, as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The figure shows the structures of the repeating units (I) and (II) ofthe polycarbonate copolymer of the invention.

1. A method for producing a polycarbonate copolymer through interfacialpolymerization, the copolymer having structural repeating unitsrepresented by formulas (I) and (II):

(wherein each of R¹ and R² represents a C1 to C6 alkyl group; Xrepresents a single bond, a C1 to C8 alkylene group, a C2 to C8alkylidene group, a C5 to C15 cycloalkylene group, a C5 to C15cycloalkylidene group, —S—, —SO—, —SO₂—, —O—, —CO—, or a bondrepresented by formula (III-1) or (III-2):

each of R³ and R⁴ represents a C1 to C3 alkyl group; Y represents a C2to C15 linear-chain or branched alkylene group; a to d are integers of 0to 4; and n is an integer of 2 to 450), characterized in that aphenol-modified diol having a hydroxybenzoic acid content of 500 ppm bymass or less is employed as a starting material.

2. A method for producing a polycarbonate copolymer as described in 1above, wherein the phenol-modified diol has a hydroxybenzoic acid alkylester content of 1.0 mass % or less.

3. A method for producing a polycarbonate copolymer as described in 1 or2 above, wherein the hydroxybenzoic acid is p-hydroxybenzoic acid.

4. A method for producing a polycarbonate copolymer as described in 2 or3 above, wherein the hydroxybenzoic acid alkyl ester is ap-hydroxybenzoic acid alkyl ester.

5. A comonomer for producing a polycarbonate resin represented byformula (IIa):

(wherein each of R³ and R⁴ represents a C1 to C3 alkyl group; Yrepresents a C2 to C15 linear-chain or branched alkylene group; c and dare integers of 0 to 4; and n is an integer of 2 to 450), characterizedin that the comonomer contains an impurity which is a hydroxybenzoicacid represented by formula (IV):

(wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4) inan amount of 500 ppm by mass or less.

6. A comonomer for producing a polycarbonate resin as described in 5above, in which the amount of a hydroxybenzoic acid alkyl ester actingas an impurity and represented by formula (V):

(wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group;and t is an integer of 0 to 4) is 1.0 mass % or less.

7. A comonomer for producing a polycarbonate resin as described in 5 or6 above, wherein n in formula (IIa) is 2 to 200.

8. A comonomer for producing a polycarbonate resin as described in anyof 5 to 7 above, which is produced through esterification between apoly(alkylene ether glycol) and a hydroxybenzoic acid represented byformula (IV):

(wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4) ora hydroxybenzoic acid alkyl ester represented by formula (V):

(wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group;and t is an integer of 0 to 4).

9. A method for producing a comonomer for producing a polycarbonateresin, characterized by comprising esterifying between a poly(alkyleneether glycol) and a hydroxybenzoic acid represented by formula (IV):

(wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4) ora hydroxybenzoic acid alkyl ester represented by formula (V):

(wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group;and t is an integer of 0 to 4), to thereby yield a reaction mixturecontaining a compound represented by formula (IIa):

(wherein each of R³ and R⁴ represents a C1 to C3 alkyl group; Yrepresents a C2 to C15 linear-chain or branched alkylene group; c and dare integers of 0 to 4; and n is an integer of 2 to 450), and,subsequently, treating the reaction mixture with an aqueous alkalinesolution.

10. A method for producing a comonomer for producing a polycarbonateresin as described in 9 above, wherein the aqueous alkaline solution hasa pH of 8 to 11.

EFFECTS OF THE INVENTION

According to the present invention, the steps of the method forproducing a PC copolymer having a specific structure from a diester diolserving as a starting material can be facilitated and reduced in number,and the impurity level of PC copolymer can be reduced.

The present invention also provides a high-purity diester diol servingas a starting material suitable for the method for producing a PCcopolymer through interfacial polymerization employing a diester diol.

BEST MODES FOR CARRYING OUT THE INVENTION

The PC copolymer produced through the production method of the presentinvention is a phenol-modified diol-copolymerized polycarbonate, and isproduced through interfacial polymerization, which is a type ofconventional production method. Specifically, in the method, a dihydricphenol, a phenol-modified diol, and a carbonate precursor such asphosgene are allowed to react. More specifically, a dihydric phenol, aphenol-modified diol, and a carbonate precursor such as phosgene areallowed to react in an inert solvent such as methylene chloride in thepresence of a known acid acceptor or molecular-weight-modifier and anoptional catalyst or branching agent.

In the present invention, a dihydric phenol described hereinbelow and aphenol-modified diol are copolymerized through interfacialpolymerization, whereby there can be produced a PC copolymer havingstructural repeating units represented by formula (I) and (II):

(wherein R¹ to R⁴, X, Y, a to d, and n will be described hereinbelow).Examples of the dihydric phenol include those represented by formula(Ia).

In formula (Ia), each of R¹ and R² represents a C1 to C6 alkyl group,and the alkyl group may be linear-chain, branched, or cyclic. Specificexamples of the alkyl group include methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl,cyclopentyl, and cyclohexyl. The numerals a and b represent the numberof substituent(s) of R¹ and that of R², respectively, and each numeralis an integer of 0 to 4. When a plurality of R's are present, these R'smay be identical to or different from one another, and when a pluralityof R²s are present, these R²s may be identical to or different from oneanother.

X represents a single bond, a C1 to C8 alkylene group (e.g., methylene,ethylene, propylene, butylene, pentylene, or hexylene), a C2 to C8alkylidene group (e.g., ethylidene or isopropylidene), a C5 to C15cycloalkylene group (e.g., cyclopentylene or cyclohexylene), a C5 to C15cycloalkylidene group (e.g., cyclopentylidene or cyclohexylidene), —S—,—SO—, —SO₂—, —O—, —CO—, or a bond represented by formula (III-1) or(III-2).

There are a variety of dihydric phenols represented by the above formula(Ia). Among them, 2,2-bis(4-hydroxyphenyl)propane (so-called bisphenolA) is particularly preferred. Examples of bisphenols other thanbisphenol A include bis(hydroxyaryl)alkanes such asbis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane,2,2-bis(4-hydroxyphenyl)phenylmethane,2,2-bis(4-hydroxy-3-methylphenyl)propane,bis(4-hydroxyphenyl)naphthylmethane,1,1-bis(4-hydroxy-t-butylphenyl)propane,2,2-bis(4-hydroxy-3-bromophenyl)propane,2,2-bis(4-hydroxy-3,5-tetramethylphenyl)propane,2,2-bis(4-hydroxy-3-chlorophenyl)propane,2,2-bis(4-hydroxy-3,5-tetrachlorophenyl)propane, and2,2-bis(4-hydroxy-3,5-tetrabromophenyl)propane;bis(hydroxyaryl)cycloalkanes such as1,1-bis(4-hydroxyphenyl)cyclopentane,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)-3,5,5-trimethylcyclohexane, and2,2′-bis(4-hydroxyphenyl)norbornene; dihydroxyaryl ethers such as4,4′-dihydroxyphenyl ether and 4,4′-dihydroxy-3,3′-dimethylphenyl ether;dihydroxydiaryl sulfides such as 4,4′-dihydroxydiphenyl sulfide and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide; dihydroxydiaryl sulfoxidessuch as 4,4′-dihydroxydiphenyl sulfoxide and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide; dihydroxydiaryl sulfonessuch as 4,4′-dihydroxydiphenyl sulfone and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone; dihydroxydiphenyls such as4,4′-dihydroxydiphenyl; dihydroxydiarylfluorenes such as9,9-bis(4-hydroxyphenyl)fluorene and9,9-bis(4-hydroxy-3-methylphenyl)fluorene; dihydroxydiaryladamantanessuch as bis(4-hydroxyphenyl)diphenylmethane,1,3-bis(4-hydroxyphenyl)adamantane, 2,2-bis(4-hydroxyphenyl)adamantane,and 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane;bis(4-hydroxyphenyl)diphenylmethane;4,4′-[1,3-phenylenebis(1-methylethylidene)]bisphenol;10,10-bis(4-hydroxyphenyl)-9-anthrone;1,5-bis(4-hydroxyphenylthio)-2,3-dioxapentaene; andα,ω-bishydroxyphenylpolydimethylsiloxane compounds. These dihydricphenols may be used singly or in combination of two or more species.

A variety of molecular-weight-modifiers may be employed so long as themodifiers can be generally employed in polymerization to form PC resin.Specific examples of monohydric phenols include phenol, o-n-butylphenol,m-n-butylphenol, p-n-butylphenol, o-isobutylphenol, m-isobutylphenol,p-isobutylphenol, o-t-butylphenol, m-t-butylphenol, p-t-butylphenol,o-n-pentylphenol, m-n-pentylphenol, p-n-pentylphenol, o-n-hexylphenol,m-n-hexylphenol, p-n-hexylphenol, p-t-octylphenol, o-cyclohexylphenol,m-cyclohexylphenol, p-cyclohexylphenol, o-phenylphenol, m-phenylphenol,p-phenylphenol, o-n-nonylphenol, m-nonylphenol, p-n-nonylphenol,o-cumylphenol, m-cumylphenol, p-cumylphenol, o-naphthylphenol,m-naphthylphenol, p-naphthylphenol, 2,5-di-t-butylphenol,2,4-di-t-butylphenol, 3,5-di-t-butylphenol, 2,5-dicumylphenol,3,5-dicumylphenol, p-cresol, bromophenol, tribromophenol,monoalkylphenols having a linear-chain or branched alkyl group havingcarbon atoms 12 to 35 (average) at o-, m-, or p-position,9-(4-hydroxyphenyl)-9-(4-methoxyphenyl)fluorene,9-(4-hydroxy-3-methylphenyl)-9-(4-methoxy-3-methylphenyl)fluorene, and4-(1-adamantyl)phenol. Among these monohydric phenols, p-t-butylphenol,p-cumylphenol, p-phenylphenol, etc. are preferably employed.

A phase-transfer catalyst is preferably employed as the catalyst, andexamples include tertiary amines and salts thereof, quaternary ammoniumsalts, and quaternary phosphonium salts. Examples of the tertiary amineinclude trithylamine, tributylamine, N,N-dimethylcyclohexylamine,pyridine, and dimethylaniline. Examples of the tertiary amine saltinclude hydrochlorides and hydrobromides of the above tertiary amines.Examples of the quaternary ammonium salt include trimethylbenzylammoniumchloride, triethylbenzylammonium chloride, tributylbenzylammoniumchloride, trioctylmethylammonium chloride, tetrabutylammonium chloride,and tetrabutylammonium bromide. Examples of the quaternary phosphoniumsalt include tetrabutylphosphonium chloride and tetrabutylphosphoniumbromide. These catalysts may be used singly or in combination of two ormore species. Among the above catalysts, tertiary amines are preferred,with triethylamine being particularly

A variety of inert organic solvents may be employed. Examples includechlorinated hydrocarbons such as dichloromethane (methylene chloride),trichloromethane, carbon tetrachloride, 1,1-dichloroethane,1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane,1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane,and chlorobenzene; toluene; and acetophenone. These organic solvents maybe used singly or in combination of two or more species. Of these,methylene chloride is preferred.

A compound having three or more functional groups may be employed as thebranching agent. Specific examples of include1,1,1-tris(4-hydroxyphenyl)ethane,4,4′-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol,α,α′,α″-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene,1-[α-methyl-α-(4′-hydroxyphenyl)ethyl]-4-[α′,α′-bis(4″-hydroxyphenyl)ethyl]benzene,phloroglucin, trimellitic acid, and isatinbis(o-cresol).

The phenol-modified diol employed in the present invention is a compoundrepresented by formula (IIa):

(wherein each of R³ and R⁴ represents a C1 to C3 alkyl group, Yrepresents a C2 to C15 linear-chain or branched alkylene group, c and dare integers of 0 to 4, and n is an integer of 2 to 450).

Examples of the alkyl group denoted by R³ or R⁴ include methyl, ethyl,n-propyl, and isopropyl. When a plurality of R³s are present, these R³smay be identical to or different from one another, and when a pluralityof R⁴s are present, these R⁴s may be identical to or different from oneanother. Examples of the C2 to C15 linear-chain or branched alkylenegroup denoted by Y include alkylene groups such as ethylene, propylene,butylene, isobutylene, pentylene, and isopentylene; and alkylideneresidues such as ethylidene, propylidene, isopropylidene, butylidene,isobutylidene, pentylidene, and isopentylidene. The “n” is preferably 2to 200, more preferably 6 to 70.

The phenol-modified diol represented by the aforementioned formula (IIa)is a compound derived from hydroxybenzoic acid, an alkyl ester thereof,or an acid chloride thereof, and a polyether-diol. Typical examples ofthe hydroxybenzoic acid alkyl ester include methyl hydroxybenzoate andethyl hydroxybenzoate. Polyether-diol is represented by HO—(Y—O)_(n)—Hand is formed of repeatedly linked C2 to C15 linear-chain or branchedalkyl ether units. Specific examples include polyethylene glycol,polypropylene glycol, and polytetramethylene glycol. Of these,polytetramethylene glycol is particularly preferred from the viewpointof availability and hydrophobicity. The recurring number (n) of theether moiety of polyether-diol is preferably 2 to 200, more preferably 6to 70. When n is 2 or more, phenol-modified diol can be effectivelycopolymerized, whereas when n is 70 or less, drop in heat resistance issmall. Needless to say, both cases are advantageous.

A typical example of the acid chloride is hydroxybenzoyl chlorideobtained from hydroxybenzoic acid and phosgene. More specifically, theacid chloride may be produced through a method disclosed in JapanesePatent No. 2652707 or other documents. Hydroxybenzoic acid or an alkylester thereof may be a p-, m-, or o-form. From the viewpoint ofcopolymerization reaction, a p-form is preferred. An o-form may exhibitpoor copolymerization reactivity due to steric hindrance the hydroxylgroup.

The phenol-modified diol employed in the present invention must have ahydroxybenzoic acid content of 500 ppm by mass or less, preferably 100ppm by mass or less. In a preferred approach, hydroxybenzoic acidspecies are removed from a phenol-modified diol on the basis ofdifference in solubility in water between the hydroxybenzoic acidcompound and the phenol-modified diol. When the method is employed,conditions such as temperature, pH, stirring conditions, separationconditions, and solvent may be appropriately selected.

The phenol-modified diol employed in the present invention preferablyhas a hydroxybenzoic acid alkyl ester content of 1.0 mass % or less,more preferably 0.5 mass % or less. In a preferred approach, ahydroxybenzoic acid alkyl ester is removed from a phenol-modified diolthrough a method in which a hydroxybenzoic acid alkyl ester is distilledout under reduced pressure, the method disclosed in Japanese PatentApplication Laid-Open (kokai) No. 62-79222. In another effectiveapproach, a hydroxybenzoic acid alkyl ester is hydrolyzed under alkalineconditions, to thereby form the corresponding hydroxybenzoic acid, whichis then subjected to the aforementioned distillation treatment forremoval.

The hydroxybenzoic acid present in the phenol-modified diol originatesfrom a starting material for synthesizing the phenol-modified diol or adecomposed species of the starting material, whereas the hydroxybenzoicacid alkyl ester originates from a starting material for synthesizingthe phenol-modified diol. Specific examples of the hydroxybenzoic acidand the hydroxybenzoic acid alkyl ester will be described hereinbelow.

In the production method of the present invention, the phenol-modifieddiol is as highly preferably as possible used in the form of methylenechloride solution in order to prevent degradation and other changes. Inthe case where the methylene chloride solution cannot be provided, anaqueous alkaline (e.g., NaOH) solution may also be employed.

In the production method of the present invention, when the proportionof copolymerized phenol-modified diol increases, flowability of theformed polymer is improved, but heat resistance decreases. Therefore,the proportion of copolymerized phenol-modified diol is preferablymodified in consideration of the balance between flowability and heatresistance of interest. When the copolymerization proportion ofphenol-modified diol is in excess of 40 mass %, the formed polymerassumes an elastomeric polymer, as disclosed in Japanese PatentApplication Laid-Open (kokai) No. 62-79222. In this case, such a polymermay fail to find the same uses as of conventional PC resin. In order tomaintain heat resistance to 100° C. or higher, the formed PC copolymerpreferably contains phenol-modified diol residues in an amount of 1 to20 mass %, more preferably 1 to 10 mass %.

The comonomer of the present invention for producing a PC resin is acompound represented by formula (IIa):

(wherein R³, R⁴, Y, c, d, and n have the same meanings as defined above)and has an amount of a hydroxybenzoic acid acting as an impurity andrepresented by formula (IV):

(wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4) of500 ppm by mass or less. The hydroxybenzoic acid content is preferably100 ppm by mass or less. In the aforementioned comonomer for producing aPC resin, through controlling the amount of impurity (hydroxybenzoicacid) to 500 ppm by mass or less, separation of the aqueous phase fromthe organic phase is facilitated during the washing step in theproduction of PC resin by interfacial polymerization.

Examples of the hydroxybenzoic acid represented by the above formula(IV) include p-hydroxybenzoic acid, m-hydroxybenzoic acid,o-hydroxybenzoic acid (salicylic acid), and these acids each having a C1to C3 alkyl group substituent on the benzene ring.

In the present invention, the comonomer for producing a PC resinpreferably has an amount of a hydroxybenzoic acid alkyl ester acting asan impurity and represented by formula (V):

(wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group;and t is an integer of 0 to 4) of 1.0 mass % or less, more preferably0.5 mass % or less. In the aforementioned comonomer for producing a PCresin, through controlling the amount of impurity (hydroxybenzoic acidalkyl ester) to 1.0 mass % or less, separation of the aqueous phase fromthe organic phase is further facilitated during the washing step in theproduction of PC resin by interfacial polymerization. In the aboveformula (V), examples of the C1 to C10 alkyl group denoted by R⁷ includethe aforementioned C1 to C3 alkyl groups, n-butyl, isobutyl, sec-butyl,t-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, and decyl.

Examples of the hydroxybenzoic acid alkyl ester represented by the aboveformula (V) include alkyl esters of the hydroxybenzoic acids. Specificexamples include methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, andn-propyl p-hydroxybenzoate.

The comonomer for producing a PC resin represented by the above formula(IIa) may be produced through esterification between the hydroxybenzoicacid represented by the above formula (IV) or the hydroxybenzoic acidalkyl ester represented by the above formula (V) and poly(alkylene etherglycol). Examples of the poly(alkylene ether glycol) includepolymethylene ether glycol, polyethylene ether glycol, and polypropyleneether glycol.

In dehydration reaction (esterification) between the hydroxybenzoic acidand the poly(alkylene ether glycol), toluene, xylene, or similar solventmay be employed as a reaction solvent. The dehydration is performedwhile the system is co-boiled at the boiling temperature of the solventso as to remove water. In the dehydration, a catalyst may beappropriately added to the system. Examples of the catalyst includesulfuric acid, phosphoric acid, p-toluenesulfonic acid, andorganometallic catalysts containing a metal such as Ti or Sn.

In dehydration-condensation reaction (esterification) between thehydroxybenzoic acid alkyl ester and the poly(alkylene ether glycol), thetwo components are caused to react in an inert gas atmosphere (e.g.,nitrogen) or under reduced pressure, while the alcohol corresponding tothe alkyl ester is released. The reaction is generally performed in theabsence of solvent at about 140 to 230° C. In the dehydration, acatalyst may be appropriately added to the system, and an organometalliccatalyst containing a metal such as Ti or Sn may be employed as thecatalyst.

In the present invention, the reaction mixture obtained through theesterification which mixture contains a compound represented by theabove formula (IIa) is treated with an aqueous alkaline solution,whereby the amount of a hydroxybenzoic acid acting as an impurity andrepresented by the above formula (IV) and that of a hydroxybenzoic acidalkyl ester acting an impurity and represented by the above formula (V)can be reduced to the aforementioned predetermined levels or lower. Inthe above treatment with aqueous alkaline solution, the followingprocedure may be employed. Specifically, the reaction mixture issubjected to liquid-liquid extraction with the aqueous alkaline solutionand an organic solvent, to thereby dissolve an impurity in the aqueousalkaline solution and dissolve the compound represented by the aboveformula (IIa) in the organic solvent, whereby the target compound isseparated from the impurity.

The aforementioned aqueous alkaline solution employed in the treatmentpreferably has a pH of 8 to 11. When the aqueous alkaline solution has apH of 8 or higher, relative amounts of impurities transferred into theorganic solvent decrease, whereby purification performance can beenhanced. When the aqueous alkaline solution has a pH of 11 or lower,lower amounts of the compound represented by formula (IIa) aretransferred into the aqueous alkaline solution, whereby product yieldcan be enhanced.

The aforementioned aqueous alkaline solution employed in the treatmentmay be an aqueous solution of an alkali metal (e.g., sodium orpotassium) or an alkaline earth metal (e.g., magnesium or calcium)hydroxide, carbonate, or hydrogencarbonate.

No particular limitation is imposed on the type of the organic solventso long as the solvent can dissolve the compound represented by formula(IIa) and can form two phases including an aqueous solution phase.Examples of employable organic solvents include aromatic hydrocarbonssuch as toluene and benzene; aliphatic and alicyclic hydrocarbons suchas hexane, heptane, and cyclohexane; ethers such as diethyl ether and1,4-dioxane; and halo-hydrocarbons such as chloroform anddichloromethane. The phase separation into the organic solvent phase andthe aqueous phase may be performed stationarily or throughcentrifugation.

In order to effectively remove an alkyl hydroxybenzoate ester acting asan impurity, alkali hydrolysis may be performed, as a preliminarytreatment, prior to the treatment with the aforementioned aqueousalkaline solution. The alkali hydrolysis may be performed under the sameconditions as employed in the treatment with the aforementioned aqueousalkaline solution. Alternatively, hydrolysis may be performed at a pH of11 or higher or under acidic conditions so as to accelerate reaction,followed by adjusting the pH to 8 to 11. During hydrolysis, the reactionsystem may be heated. The reaction field under which alkali hydrolysisis performed may be a single aqueous solution phase or an aqueoussolution/organic solvent dual-phase.

EXAMPLES

The present invention will next be described in more detail by way ofexamples, which should not be construed as limiting the inventionthereto. In the Examples hereinbelow, the impurity content wasdetermined through the following method.

<Determination of Impurity Content>

Measurement was performed through HPLC (high-performance liquidchromatography) under the following conditions, and the impurity contentwas determined from the calibration curve given from the data of thestandard sample.

-   -   Column: ODS-3, product of GL Science    -   Column temperature: 40° C.    -   Solvent: 0.5 mass % aqueous phosphoric acid-acetonitrile 1:2        (vol.)    -   Flow rate: 1.0 mL/min

Comparative Example 1 and Example 1 Synthesis of Phenol-modified Diols(A-1) and (A-2)

Under nitrogen, polytetramethylene glycol (PTMG, Mn=1000) (100 g) andmethyl p-hydroxybenzoic acid (33.4 g) were heated in the presence ofdibutyltin oxide (0.5 g) at 220° C., and formed methanol was distilledout.

Under reduced pressure in the reaction system, excessive methylp-hydroxybenzoate was removed, to thereby yield a crude product ofphenol-modified diol (A-1) (Comparative Example 1). The crude product(A-1) (5.0 g) was dissolved in methylene chloride (30 mL), and a 8-mass% aqueous sodium hydrogencarbonate solution (10 mL) was added to themethylene chloride solution. The mixture was vigorously agitated for 20minutes, and the methylene chloride phase was collected throughcentrifugation. The thus-collected methylene chloride phase wascondensed under reduced pressure, to thereby yield a purified product ofphenol-modified diol (A-2) (Example 1). The p-hydroxybenzoic acidcontent and the methyl p-hydroxybenzoate content of crude product (A-1)and purified product (A-2) were determined through HPLC(high-performance liquid chromatography) on the basis of theaforementioned method. The similar determination procedure was employedfor phenol-modified diols produced in the Examples and ComparativeExamples hereinbelow. Table 1 shows the results.

Examples 2 and 3 Synthesis of Phenol-modified Diols (A-3) and (A-4)

The procedure of Example 1 was repeated, but removal of excessive methylp-hydroxybenzoate was terminated before completion of the removal. Thethus-obtained phenol-modified diol (10 g) was dissolved in methylenechloride (60 mL), and a 8-mass % aqueous sodium hydrogencarbonatesolution (20 mL) was added to the methylene chloride solution. Themixture was vigorously agitated for 20 minutes, and the methylenechloride phase was collected through centrifugation. The thus-collectedmethylene chloride phase was condensed under reduced pressure, tothereby yield phenol-modified diol (A-3) (Example 2).

The above-produced phenol-modified diol (A-3) and the phenol-modifieddiol (A-1) produced in Example 1 were mixed at a ratio by mass of 6:4,to thereby yield phenol-modified diol (A-4) (Example 3).

Comparative Example 2 and Examples 4 and 5 Synthesis of Phenol-modifiedDiols (B-1) to (B-3)

The procedures of Comparative Example 1 and Examples 1 and 2 wererepeated, except that polytetramethylene glycol (Mn=2000) was usedinstead of polytetramethylene glycol (Mn=1000), to thereby yieldphenol-modified diols (B-1) to (B-3), corresponding to phenol-modifieddiols (A-1) to (A-3), respectively.

Comparative Example 3 and Example 6 Synthesis of Phenol-modified Diols(C-1) and (C-2)

The procedures of Comparative Example 1 and Example 1 were repeated,except that polytetramethylene glycol (Mn=600) was used instead ofpolytetramethylene glycol (Mn=1000), to thereby yield phenol-modifieddiol crude product (C-1) and phenol-modified diol purified product(C-2), respectively.

Comparative Example 4 and Example 7 Synthesis of Phenol-modified Diols(D-1) and (D-2)

The procedures of Comparative Example 1 and Example 1 were repeated,except that polytetramethylene glycol (Mn=2900) was used instead ofpolytetramethylene glycol (Mn=1000), to thereby yield phenol-modifieddiol crude product (D-1) and phenol-modified diol purified product(D-2), respectively.

Comparative Example 5 and Example 8 Synthesis of Phenol-modified Diols(E-1) and (E-2)

The procedures of Comparative Example 1 and Example 1 were repeated,except that polyethylene glycol (PEG) (Mn=400) was used instead ofpolytetramethylene glycol (Mn=1000), to thereby yield phenol-modifieddiol crude product (E-1) and phenol-modified diol purified product(E-2), respectively.

Example 9 Production of Polycarbonate Copolymer

(1) PC Oligomer Synthesizing Step

To a 5.6-mass % aqueous sodium hydroxide solution, sodium dithionite wasadded in an amount of 0.2 mass % with respect to bisphenol A (BPA),which was to be added to the aqueous solution. Then, the BPA wasdissolved in the aqueous solution in such an amount that the BPAconcentration was adjusted to 13.5 mass %, whereby an aqueous sodiumhydroxide solution of BPA was prepared. The aqueous sodium hydroxidesolution of BPA was continuously fed to a tube reactor (inner diameter:6 mm, tube length: 30 m) at 40 L/hr, and methylene chloride and phosgenewere also continuously fed to the reactor at 15 L/hr and 4.0 kg/hr,respectively. The tube reactor has a jacket section, through whichcooling water was circulated so as to maintain the reaction mixture at40° C. or lower.

The reaction mixture supplied through the tube reactor was continuouslyfed to a tank reactor (inner volume: 40 L) equipped with a retreatedblade and a baffle plate. To the tank reactor, the aqueous sodiumhydroxide solution of BPA (2.8 L/hr), a 25-mass % aqueous sodiumhydroxide solution (0.07 L/hr), water (17 L/hr), and a 1-mass % aqueoustriethylamine solution (0.64 L/hr) were fed, and the mixture was allowedto react at 29 to 32° C. The reaction mixture was continuously removedfrom the tank reactor and allowed to stand, whereby the aqueous phasewas separated out and the methylene chloride phase was collected. Thethus-produced polycarbonate oligomer solution was found to have anoligomer concentration of 329 g/L and a chloroformate concentration of0.74 mol/L.

(2) Polymerization Step for Producing PC Copolymer

Into a tank reactor (inner volume: 1 L) equipped with baffle plates anda paddle-form agitation blade, the oligomer solution (137 mL), thephenol-modified diol methylene chloride solution (A-2) produced inExample 1, and triethylamine (85 μL) were placed. To the mixture, a6.4-mass % aqueous sodium hydroxide solution (19.2 g) was added understirring, and the mixture was allowed to react for 10 minutes.Subsequently, a PTBP methylene chloride solution (PTBP (1.47 g)dissolved in methylene chloride (10 mL)), and an aqueous BPA sodiumhydroxide solution (NaOH (4.90 g) and sodium dithionite (16 mg)dissolved in water (71 mL), then BPA (8.06 g) dissolved in the aqueoussolution) was added to the reaction mixture, and the resultant mixturewas allowed to polymerize for 50 minutes.

The polymerization product was diluted with methylene chloride (100 mL),followed by stirring for 10 minutes. An aliquot (50 mL) of thepolymerization liquid was taken into a 50-mL messcylinder and was leftto stand. Separation of the liquid into the aqueous phase and themethylene chloride phase was observed. The remaining polymerizationliquid was centrifuged, thereby collecting another methylene chloridephase. The methylene chloride phase (240 mL) was placed in the reactorwhich had been employed for polymerization. A 0.03-mol/L aqueous NaOHsolution (42 mL) was added to the methylene chloride phase, and themixture was stirred for 10 minutes. The liquid mixture (50 mL) was takeninto a 50-mL messcylinder and was left to stand. Separation of theliquid into the aqueous phase and the methylene chloride phase wasobserved.

The remaining polymerization liquid was centrifuged, thereby collectinganother methylene chloride phase. The methylene chloride phase (150 mL)was washed with 0.2-mol/L hydrochloric acid then twice with deionizedwater, for purification. Solvent was removed from the thus-purifiedmethylene chloride phase, to thereby yield a purified PC copolymer.Viscosity number, copolymerization proportion, and glass transitiontemperature Tg of the PC copolymer were determined through the followingprocedures. Table 1 shows the results.

(1) Determination of Viscosity Number

Determined in accordance with ISO 1628-4 (1999)

(2) Determination of Copolymerization Proportion

¹H-NMR of the copolymer was measured. Proton (underlined) peaks wereassigned as follows.

-   δ1.4-1.9: CH₃ (BPA), —O—CH₂—CH₂ —CH₂ —CH₂—-   δ3.3-3.5: —O—CH₂ —CH₂—CH₂—CH₂ —-   δ4.3-4.4: —CO—O—CH₂ —CH₂—CH₂ —CH₂—

From the respective integral peak strengths, the ratio by mole of thephenol-modified diol carbonate segment represented by the above formula(II) to the BPA carbonate segment represented by the above formula (I)was calculated, and the value was reduced to a mass-based value. Oneexample of the calculation procedure is as follows.

Calculation Example

When the integral peak values of δ1.4-1.9, δ3.3-3.5, and δ4.3-4.4 are858.6, 118.7, and 10.21, respectively, unit repetition number (n) is asfollows.n=118.7÷10.21+1=12.6Thus, BPA peak value and phenol-modified diol peak value are as follows.BPA=[(858.6−118.7−10.21)/6]=121.6phenol-modified diol=(10.21/4)=2.55

The ratio by mole of the BPA carbonate segment is calculated to be 97.9mol % through the following relationship.[(858.6−118.7−10.21)/6]/{(10.21/4)+[(858.6−118.7−10.21)/6]}×100=97.9 mol%

The ratio by mole of the phenol-modified diol carbonate segment iscalculated to be 2.05 mol % through the following relationship.(10.21/4)/{(10.21/4)+[(858.6−118.7−10.21)/6]}×100=2.05 mol %

Accordingly, the proportion of copolymerized phenol-modified diolcarbonate segment [mass %] is calculated to be 8.6 mass % through thefollowing relationship.2.05×(136+120+12.6×72+12+16)÷(2.05×(136+120+12.6×72+12+16)+97.9×254)×100=8.9mass %(3) Determination of Glass Transition Temperature Tg

Determined in accordance with ISO 11357

Examples 10 to 16 and Comparative Examples 6 to 10

The procedure of Example 9 was repeated, except that phenol-modifieddiols shown in Table 1 were used instead of phenol-modified diol (A-2)and PTBP was added in an amount shown in Table 1, to thereby yield PCcopolymers. In a manner similar to that employed in Example 9, viscositynumber, copolymerization proportion, and glass transition temperature Tgof the PC copolymers were determined. Table 1 shows the results.

TABLE 1 Comp. Comp. Ex. 9 Ex. 10 Ex. 11 Ex. 6 Ex. 12 Ex. 13 Ex. 7Phenol- Type A-2 A-4 A-1 B-2 B-3 B-1 modified Mn of PTMG or PEG 1,0001,000 1,000 1,000 2,000    2,000    2,000 diol p-hydroxybenzoic 90 90400 900 10>  10>  1200 acid [mass ppm] p-hydroxybenzoic 0.2 0.8 0.9 0.90.4 0.9 0.9 acid methyl ester [mass %] Amount of PTBP used [g] 1.33 1.331.33 1.33  1.26  1.26 1.26 Volume of Separation of 9.0 9.0 5.0 0 9.0 9.00 separated polymerization aqueous liquid phase Volume of 9.0 7.5 4.0 09.0 7.0 0 [mL]* separated aqueous phase after washing with alkali PCViscosity number 45.8 46.0 45.0 44.0 47.7  47.0  47.6 copolymerCo-polymerization 8.9 8.9 8.9 8.9 8.9 8.9 8.9 proportion [mass %] Tg [°C.] 113 113 113 113 108   108   108 Comp. Comp. Comp. Ex. 14 Ex. 8 Ex.15 Ex. 9 Ex. 16 Ex. 10 Phenol- Type C-2 C-1 D-2 D-1 E-2 E-1 modified Mnof PTMG or PEG 600   600 2,900 2,900 400   400 diol p-hydroxybenzoic10>  1200 80 800 10>  900 acid [mass ppm] p-hydroxybenzoic 0.4 0.5 0.90.9 0.2 0.2 acid methyl ester [mass %] Amount of PTBP used [g]  1.751.75 1.75 1.75  1.26 1.26 Volume of Separation of 9.0 0 9.0 1.5 8.0 0separated polymerization aqueous liquid phase Volume of 9.5 0 9.5 0 7.50 [mL]* separated aqueous phase after washing with alkali PC Viscositynumber 40.0  40.0 39.2 39.0 47.4  47.4 copolymer Co-polymerization 8.88.8 8.8 8.8 8.9 8.9 proportion [mass %] Tg [° C.] 110   110 103 103111   111 *After each sample had been left to stand for one hour

Comparative Example 11

Into a flask (inner volume: 1 L) equipped with a nitrogen conduit, avacuum apparatus, a thermometer, and a stirrer, polytetramethyleneglycol (Mn (number average molecular weight)=2000) (200 g, 0.1 mol),methyl p-hydroxybenzoate (30.4 g, 0.2 mol), tetrabutyl titanate (2 mL),and magnesium acetate (0.5 g) were placed. The mixture was heated to 80to 100° C. under nitrogen until the mixture was melted. Subsequently,the molten mixture was gradually heated to 230° C. in vacuum. Themixture was cooled in vacuum, whereby the correspondingpolytetramethylene glycol bis(p-hydroxybenzoic acid ester) was yielded.The impurity content of the compound is shown in Table 2.

Example 17

The compound (50 g) obtained in Comparative Example 11 was dissolved inmethylene chloride (400 mL), and the solution was transferred into aflask (inner volume: 2 L) equipped with a stirrer. A 0.3-mol/L aqueousNaHCO₃ solution (400 mL) was added to the above methylene chloridesolution with mixing, and the mixture was allowed to stand, whereby themethylene chloride phase was separated from the liquid. The methylenechloride phase was mixed with water (200 mL), and the mixture wasallowed to stand, to thereby collect another methylene chloride phase.Methylene chloride was removed from the phase by means of an evaporator,and the residue was dried at 40° C. under reduced pressure for onenight. The impurity content of the thus-obtained purified product isshown in Table 2.

Example 18

The procedure of Comparative Example 11 was repeated, except thatpolyethylene glycol (Mn=3400) (340 g, 0.1 mol) was used instead ofpolytetramethylene glycol, to thereby yield the polyethylene glycolbis(p-hydroxybenzoic acid ester). The compound was purified in a mannersimilar to that employed in Example 17. The impurity content of thethus-obtained purified compound is shown in Table 2.

Comparative Example 12

Into a reactor equipped with a protective gas conduit,polytetramethylene glycol (Mn=1000) (800 g, 0.8 mol) and methylp-hydroxybenzoate (243 g, 1.6 mol) were placed, and the mixture washeated at 140° C. so as to homogenize the mixture. Tin octanate (3.9 g)was added to the mixture, followed by heating to 180° C., wherebyrelease of methanol was initiated. After completion of release ofmethanol, the mixture was stirred at 180° C. for one hour, and theproduct was cooled, to thereby yield the correspondingpolytetramethylene glycol bis(p-hydroxybenzoic acid ester). The impuritycontent of the compound is shown in Table 2.

Example 19

The compound produced in Comparative Example 12 (50 g) was purified in amanner similar to that employed in Example 17. The impurity content ofthe thus-obtained purified compound is shown in Table 2.

Example 20

The compound produced in Comparative Example 12 (50 g) was dissolved ina 0.5-mol/L aqueous sodium hydroxide solution (400 mL), and the solutionwas transferred into a flask (inner volume: 2 L) equipped with a stirrerand stirred for one hour. A 2-mol/L hydrochloric acid was graduallyadded dropwise to the solution, to thereby regulate pH to 9. Methylenechloride (400 mL) was added to the solution, and the mixture was allowedto stand, whereby the methylene chloride phase was separated from theliquid. The methylene chloride phase was mixed with water (200 mL), andthe mixture was allowed to stand, to thereby collect another methylenechloride phase. Methylene chloride was removed from the phase by meansof an evaporator, and the residue was dried at 40° C. under reducedpressure for one night. The impurity content of the thus-obtainedpurified product is shown in Table 2.

Comparative Example 13

Into a reactor (inner volume: 1 L) equipped with a Dean-Stark apparatusand a nitrogen conduit, polytetramethylene glycol (Mn=1000) (500 g, 0.5mol), p-hydroxybenzoic acid (138 g, 1.0 mol), titanium potassium oxalate(0.26 g, 0.0007 mol), and xylene (100 g) were placed, and the mixturewas allowed to dehydration-condense (esterify) at 190° C. under refluxconditions with xylene. The reaction completed for five hours. Aftercompletion of the reaction, xylyene was distilled out, to thereby yieldthe corresponding polytetramethylene glycol bis(p-hydroxybenzoic acidester). The impurity content of the compound is shown in Table 2.

Example 21

The compound produced in Comparative Example 13 (50 g) was purified in amanner similar to that employed in Example 17. The impurity content ofthe thus-obtained purified compound is shown in Table 2.

TABLE 2 p-Hydroxybenzoic Methyl p- acid (ppm by mass) hydroxybenzoate(mass %) Comp. Ex. 11 800 0.6 Ex. 17 10 0.4 Ex. 18 50 0.4 Comp. Ex. 121,000 1.5 Ex. 19 100 1.2 Ex. 20 200 0.3 Comp. Ex. 13 6,000 Not detectedEx. 21 400 Not detected

Comparative Example 14 (Production of PC Copolymer)

(1) PC Oligomer Preparation Step

BPA was dissolved in a 5.6-mass % aqueous sodium hydroxide solution insuch an amount that the bisphenol (BPA) concentration was adjusted to13.5 mass %, whereby an aqueous sodium hydroxide solution of BPA wasprepared. The aqueous sodium hydroxide solution of bisphenol A wascontinuously fed to a tube reactor (inner diameter: 6 mm, tube length:30 m) at 40 L/hr, and methylene chloride and phosgene were alsocontinuously fed to the reactor at 15 L/hr and 4.0 kg/hr, respectively.The tube reactor has a jacket section, through which cooling water wascirculated so as to maintain the reaction mixture at 40° C. or lower.

The reaction mixture supplied through the tube reactor was continuouslyfed to a tank reactor (inner volume: 40 L) equipped with a retreatedblade and a baffle plate. To the tank reactor, the aqueous sodiumhydroxide solution of BPA (2.8 L/hr), a 25-mass % aqueous sodiumhydroxide solution (0.07 L/hr), water (17 L/hr), and a 1-mass % aqueoustriethylamine solution (0.64 L/hr) were fed, and the mixture was allowedreact at 29 to 32° C. The reaction mixture was continuously removed fromthe tank reactor and allowed to stand, whereby the aqueous phase wasseparated out and the methylene chloride phase was collected. Thethus-produced polycarbonate oligomer solution was found to have anoligomer concentration of 329 g/L and a chloroformate concentration of0.74 mol/L.

(2) Polymerization Step for Producing PC Copolymer

Into a tank reactor (inner volume: 1 L) equipped with four baffle platesand a paddle-form agitation blade, the oligomer solution (137 mL)obtained in the step (1) above, methylene chloride (88 mL), and thecompound produced in Comparative Example 11 (5 g) were placed.Subsequently, triethylamine (85 μL) were added to the reactor. To themixture, a 6.4-mass % aqueous sodium hydroxide solution (18 mL) wasadded under stirring, and the mixture was allowed to react for 10minutes.

To the reaction mixture, p-tert-butylphenol (1.18 g) dissolved inmethylene chloride (10 mL) and bisphenol A (8.1 g) dissolved in a6.4-mass % aqueous sodium hydroxide solution (71 mL) were added, and theresultant mixture was allowed to react for further 50 minutes.

(3) Washing Step

Methylene chloride (100 mL) was added to the reaction mixture obtainedin the step (2) above, and the resultant mixture (50 mL) was taken intoa 50-mL messcylinder with continuous stirring, and allowed to stand. Theseparation status of the solution in the messcylinder was observed. Thetime required for the methylene chloride phase to be separated in thesystem was measured. The time was evaluated as separation time.

From the remaining solution, the methylene chloride phase was removed.The solution was sequentially washed with 15 vol. % (with respect to thesolution) of an 0.03-mol/L aqueous sodium hydroxide solution, with0.2-mol/L hydrochloric acid, and twice with pure water. The aqueousphase was confirmed to have an electrical conductivity of 0.01 μS/m orless after washing.

(4) Flake Production Step

A methylene chloride solution of the PC resin obtained in the step (3)above was condensed, followed by pulverization, to thereby form resinflakes. The thus-produced flakes were dried at 100° C. under reducedpressure. Viscosity number of the PC resin was determined in accordancewith ISO 1628-4 (1999). The results are shown in Table 3.

Examples 22 to 26 and Comparative Examples 15 and 16

The procedure of Comparative Example 14 including 14(2) was repeated,except that compounds obtained in Examples 17 to 21 and ComparativeExamples 12 and 13 were used instead of the compound obtained inComparative Example 11. The same measurement was performed. The resultsare shown in Table 3.

TABLE 3 Separation Viscosity Comonomer time (min) number of PC Comp. Ex.14 Comp. Ex. 11 58 47.0 Ex. 22 Ex. 17 14 46.6 Ex. 23 Ex. 18 18 47.2Comp. Ex. 15 Comp. Ex. 12 ≧60 46.5 Ex. 24 Ex. 19 30 46.2 Ex. 25 Ex. 2019 45.8 Comp. Ex. 16 comp. Ex. 13 ≧60 45.7 Ex. 26 Ex. 21 28 46.0

INDUSTRIAL APPLICABILITY

According to the present invention, a PC copolymer having a specificstructure can be produced from a diester diol serving as a startingmaterial at high productivity.

In addition, through use of the comonomer of the present invention forproducing a PC resin, a PC copolymer can be produced at highproductivity.

1. A method for producing a polycarbonate copolymer comprisingstructural repeating units represented by formulas (I) and (II):

wherein each of R¹ and R² independently represents a C1 to C6 alkylgroup; X represents a single bond, a C1 to C8 alkylene group, a C2 to C8alkylidene group, a C5 to C15 cycloalkylene group, a C5 to C15cycloalkylidene group, —S—, —SO—, —SO₂—, —O—, —CO—, or a grouprepresented by formula (III-1) or (III-2):

each of R³ and R⁴ independently represents a C1 to C3 alkyl group; Yrepresents a C2 to C15 linear-chain or branched alkylene group; a to dare independently integers of 0 to 4; and n is an integer of 2 to 450,by reacting (A) a dihydric phenol, (B) a phenol-modified diol and (C) acarbonate precursor, wherein the phenol-modified diol (B) is representedby formula (IIa) and comprises 500 ppm by mass or less of ahydroxybenzoic acid:

where R³, R⁴, Y, c, d and n are as defined above.
 2. A method forproducing a polycarbonate copolymer as described in claim 1, wherein thephenol-modified diol has a hydroxybenzoic acid alkyl ester content of1.0 mass % or less.
 3. A method for producing a polycarbonate copolymeras described in claim 1, wherein the hydroxybenzoic acid isp-hydroxybenzoic acid.
 4. A method for producing a polycarbonatecopolymer as described in claim 2, wherein the hydroxybenzoic acid alkylester is a p-hydroxybenzoic acid alkyl ester.
 5. A comonomer representedby formula (IIa):

wherein each of R³ and R⁴ independently represents a C1 to C3 alkylgroup; Y represents a C2 to C15 linear-chain or branched alkylene group;c and d are independently integers of 0 to 4; and n is an integer of 2to 450, wherein the amount of a hydroxybenzoic acid represented byformula (IV) present therein is 500 ppm by mass or less:

wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to
 4. 6.A comonomer as claimed in claim 5, in which the amount of ahydroxybenzoic acid alkyl ester represented by formula (V) therein is1.0 mass % or less:

wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group; andt is an integer of 0 to
 4. 7. A comonomer as described in claim 5,wherein n in formula (IIa) is 2 to
 200. 8. A comonomer as described inclaim 5, which is produced through esterification between apoly(alkylene ether glycol) and a hydroxybenzoic acid represented byformula (IV):

wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4and/or a hydroxybenzoic acid alkyl ester represented by formula (V):

wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group; andt is an integer of 0 to
 4. 9. A method for producing a comonomercomprising esterifying a poly(alkylene ether glycol) with ahydroxybenzoic acid represented by formula (IV):

wherein R⁵ is a C1 to C3 alkyl group, and s is an integer of 0 to 4and/or a hydroxybenzoic acid alkyl ester represented by formula (V):

wherein R⁶ is a C1 to C3 alkyl group; R⁷ is a C1 to C10 alkyl group; andt is an integer of 0 to 4, to yield a reaction mixture comprising acompound represented by formula (IIa):

wherein each of R³ and R⁴ independently represents a C1 to C3 alkylgroup; Y represents a C2 to C15 linear-chain or branched alkylene group;c and d are independently integers of 0 to 4; and n is an integer of 2to 450, and, subsequently, treating the reaction mixture with an aqueousalkaline solution.
 10. A method for producing a comonomer as describedin claim 9, wherein the aqueous alkaline solution has a pH of 8 to 11.